Conventional residential heating systems utilize a heating source, such as an oil or gas furnace that uses a flame or electric systems that use resistance heating elements, to heat a transfer medium that carries heat into the area to be heated. Many furnaces using fossil fuels to generate heat apply that heat to water that is then circulated to heat exchangers within the area to be heated such that heat energy is extracted from the heated water and used to warm the air within the area to be heated. Water is generally the choice for the heat transfer medium as water is readily available and is inexpensive. However, water will freeze and expand at 32° F. (0° C.) and can cause damage to the heating system and the corresponding structure if not operated during sub-freezing temperatures. Furthermore, water can create corrosion as the temperature of the water is increased. Also, water is limited with respect to a maximum temperature at which the heating system can be operated as water will boil at 212° F. (100° C.).
In an attempt to alleviate these operational limitations of using water as the heat transfer medium, some heating systems have added either ethylene or propylene glycol to the water to both lower the freezing point and raise the boiling point of the heat transfer medium. Alcohol has also been added to water for the same purposes, but alcohol is very volatile and flammable, and can provide a dangerous solution for use as a heat transfer medium.
Heat transfer mediums should ideally be fluid and operable at a broad range of temperatures, have low viscosities to facilitate pumping the heat transfer medium through the heating system particularly at low temperatures, and provide an effective rate of heat transfer. Furthermore, the heat transfer fluid should have a sufficiently low freezing point, decompose slowly during use, and not corrode the system in which the heat transfer fluid is being utilized. In addition, it would be desirable that the heat transfer fluid be environmentally friendly in case the fluid is spilled into the environment. Accordingly, density, thermal conductivity, specific heat, kinematic viscosity, environmental impact, toxicity, flammability and corrosive nature are specific parameters that are important in the effectiveness of a heat transfer medium.
Choosing an appropriate heat transfer fluid can be operable to maximize the effectiveness and the efficiency of a heating system whether used in residential, industrial or commercial applications. An efficient transfer of heat energy from a heating source to an area to be heated will reduce heating costs and reduce the emission of hydrocarbons into the atmosphere.
A heat transfer fluid is disclosed in U.S. Pat. No. 3,407,142, granted on Oct. 27, 1968, to Robert S. McCord and assigned to McDonnell Douglas Corporation in which the heat transfer fluid for use in low temperature conditions, particularly with aircraft and electronic systems. This heat transfer fluid consists essentially of a tetraalkyl orthosilicate and a polyalkylene glycol diether to provide a novel cooling fluid for use in aircraft and electronic systems at very low temperatures.
A heat transfer system is disclosed in U.S. Pat. No. 7,476,332, granted on Jan. 13, 2009, to Hari Babu Sunkara and assigned to E. I. Du Pont De Nemours & Company in which the heat transfer fluid comprises a polytrimethylene homo- or copolyether glycol with a blending component selected from the group consisting of ethylene glycol, diethylene glycol, polyalkylene glycol copolymers of ethylene oxide and propylene oxide, vegetable oils, aromatic compounds, mineral oil, silicone fluids, and mixtures thereof. This heat transfer fluid is intended to be used in automobiles, industrial heat exchangers, heat recovery units, refrigeration units, solar panels, cooling towers, transformers, and heating radiators.
U. S. Patent Application Publication No. 2008/0315152, filed by Glendon C. Daly and published on Dec. 25, 2008, discloses a heat transfer fluid comprised of glycerin or glycerol. In one embodiment, the glycerin contains greater than 95% by weight glycerol, or can be crude glycerin. This heat transfer fluid is intended for use in heating and cooling systems applicable to buildings, whether residential, industrial or commercial.
It would be desirable to provide a heating system utilizing a heat transfer fluid that maximizes the efficiency of the operation of the heating system for use in residential, industrial or commercial applications.